Various techniques have been developed for geometrically calibrating the projectors of multi-projector displays. In some geometric calibration approaches, one or more cameras provide feedback data relating to the images that are projected by the different projectors and projector calibration data is computed from the camera feedback data. The images projected by the projectors are geometrically aligned in accordance with the projector calibration data to generate seamless composite images. However, this calibration process can be negatively affected by the occurrences of “hotspots”.
Hotspots are bright areas (diffuse versions of the projector's lamp and lens) that are seen by the viewer through the screen. These hotspots move with respect to the viewing angle and are more intense with higher gain screens. Because these hotspots move with respect to the viewing angle, it is possible to account for them at one angle (e.g looking straight at the screen from the front) but not at another angle (e.g. looking at the screen from the side). Consequently, these hotspots can adversely affect the calibration of the projection system and present a significant problem for the calibration process.